Iran says it plans to greatly expand its nuclear program - a day after Tehran announced it can now enrich uranium on an "industrial scale."
The head of the country's atomic energy organization, Gholam Reza Aghazadeh, said Tuesday that Iran plans to eventually install 50,000 centrifuges at its Natanz nuclear facility.
Iran's top nuclear negotiator, Ali Larijani, said Monday that Iran has begun to feed uranium gas into 3,000 centrifuges at Natanz for enrichment.
That announcement drew criticism from the United States, the United Nations and the European Union.
Russia expressed skepticism, with Foreign Minister Sergei Lavrov saying that Moscow has no information to confirm Iran's statement.
Two U.N. nuclear inspectors arrived in Iran Tuesday, for a scheduled visit to the Natanz site, and could provide the first independent verification of Iran's claim.
The United States and its allies accuse Iran of trying to develop nuclear weapons. Iran says its nuclear program is for the peaceful production of energy.
The U.N. Security Council has passed two resolutions since December imposing sanctions on for its refusal to suspend its uranium enrichment program.
Iran has said it may have to reconsider its membership in the nuclear Non-Proliferation Treaty - if it is subjected to further pressure over its nuclear program.
Some information for this report was provided by AFP, AP and Reuters.